Consumers associate certain aromas with certain products. If the product lacks the aroma associated with it, consumer perception of the product is adversely affected. This is particularly a problem in the field of instant coffees, although it also exists in other fields. For ease of description, the problem is described in this specification primarily with reference to instant coffees, although the invention is not limited to this application.
Instant coffee powders which are obtained from commercial processes involving extraction, concentration and drying, are usually substantially aromaless. For this reason, it is conventional to trap coffee aromas which are given off during the processing of the instant coffee and to reincorporate these aromas into the instant coffee powder.
Usually the aroma is reincorporated by first capturing the aroma into a substrate such as an oil or emulsion. The aroma-containing substrate is then usually sprayed on the instant coffee powder prior to handling and blending. The blended coffee powders are later filled into jars which are then sealed. Although this process works well, significant amounts of aroma are lost between spraying of the aroma-containing substrate on the coffee powder and filling of the jars.
One attempt to solve the problem is described in U.S. Pat. No. 3,769,032. Here filled coffee jars are transported to beneath a mechanical syringe which contains coffee aroma. The syringe descends into each jar until the needle tip is near the bottom of the jar. The syringe then rises and at the same time injects droplets of coffee aroma into the coffee product in the jar. The droplets should have a size of about 0.5 mm to 3 mm. Although the results reported in the patent indicate good reincorporation of the coffee aroma, the system would not be feasible in a high-speed production line.
Another attempt is disclosed in U.S. Pat. Nos. 4,355,571, 4,496,596 and 4,871,564. Here the coffee aroma is injected into a flowing stream of the coffee powder immediately prior to filling of the coffee powder into jars.
It is also known from European patent application 0047169 to spray coffee aroma onto the inner surface of containers for single serving packets of coffee powder. Thereafter the coated packets are filled with coffee powder and sealed. Although it is mentioned in the patent application that the containers may be "bottles, jars, cans, pouches, bags, envelopes and the like", it is clear that the procedure is intended for small disposable packages made from flexible foils and films. The reason is that it would not be practicable to spray and use bottles, jars and cans of a single serving size.
However, the procedure described in the European application is not readily applicable to more rigid containers, such as jars and bottles, which are of a size which contain multiple servings of the product. Further, since single-serving packets are not transparent and are usually opened by tearing off a comer, it does not matter if the coffee aroma forms unsightly streaks on the insides of the packet. This is not the case for containers which contain multiple servings of the product since they are usually transparent; at least in parts.